This disclosure relates to a fan drive gear system integrated carrier and torque frame.
One type of gas turbine engine includes a fan drive gear system that is mechanically arranged between the turbo-machinery of the engine and a fan. The turbo-machinery is composed of two concentric shafts rotating at different speeds containing independent compressors and turbines. The turbo-machinery rotationally drives the fan, via the gear system, to move fluid through a nacelle which divides the fluid flow into two streams. An inner stream supplies the turbo-machinery and the outer stream consists of fluid which bypasses the inner stream and is solely compressed and moved by the fan.
Typically the fan drive gear system is provided by an epicyclic gear train and includes a centrally located input gear driven by the turbo-machinery, intermediate gears circumferentially arranged about and intermeshing with the input gear and a ring gear provided about and intermeshing the intermediate gears. Depending upon the configuration, either the intermediate gears or the ring gear rotationally drives the fan in response to rotation of the input gear.
The intermediate gears are typically supported in a carrier by a journal extending between spaced apart walls of the carrier. The carrier is typically constructed from a high strength metallic alloy such as steel, titanium or nickel. The carrier is bolted to a torque frame, which is secured to fixed structure or rotating structure depending upon the particular type of gear system.
One type of gear system for helicopter applications has been used which directly supports the intermediate gears on an integrated carrier and torque frame. This integrated torque frame includes shafts that directly support the intermediate gears in a cantilevered fashion by conventional rolling element bearings. This arrangement is subjected to vibrational stresses that may cause the integrated torque frame to fail.